During a trip on an expressway, Don travelled a total of x miles. His average speed on a certain 5 -mile section of the expressway was 30 miles per hour, and his average speed for the remainder of the trip was 60miles per hour. His travel time for the x-mile trip was what percent greater than it would have been if he had travelled at a constant rate of 60 miles per hour for the entire trip?
(A) 8.5
(B) 50
(C) x/12
(D) 60/x
(E) 500/x
GMATPrep
a trip on an expressway
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- sanju09
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- HSPA
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Let x=65
For 5 miles he needs 10 minutes. for next 60 miles he needs 60min
case 2: 60m/h constant
he needs 65 min for 65 miles
How much 70 min is greater than to 65 min
5/65 *100 So I am going with E
For 5 miles he needs 10 minutes. for next 60 miles he needs 60min
case 2: 60m/h constant
he needs 65 min for 65 miles
How much 70 min is greater than to 65 min
5/65 *100 So I am going with E
- selango
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Total Distance=X miles,Speed =60 miles/hr
Normal time taken=X/60
D1=5 miles S1=30 miles/hr,T1=1/6
D2=x-5 miles S2=60 miles/hr,T2=x-5/60
Total time taken=(1/6)+(x-5)/60
Percentage=([1/6)+(x-5)/60-(x/60)]/[(x/60)] * 100
=500/x
Pick E
Normal time taken=X/60
D1=5 miles S1=30 miles/hr,T1=1/6
D2=x-5 miles S2=60 miles/hr,T2=x-5/60
Total time taken=(1/6)+(x-5)/60
Percentage=([1/6)+(x-5)/60-(x/60)]/[(x/60)] * 100
=500/x
Pick E
--Anand--